This invention relates to a power module of an inverter circuit which supplies electric power to an alternating current motor.
A technique is known whereby a direct current is converted to an alternating current of a predetermined frequency and a predetermined voltage by an inverter in order to obtain an alternating current which drives an alternating current motor. The direct current is obtained by supplying it from battery current or by rectifying alternating current with a converter or a rectifier circuit.
When an alternating current is generated in the inverter, a magnetic field is also formed around the current flow. Such a magnetic field may adversely affect to the electronic parts in the vicinity when it becomes large.
It is therefore an object of this invention to suppress the formation of the magnetic field in the inverter.
It is another object of this invention to make an inverter circuit more compact.
It is yet another object of this invention to make the space occupied by an alternating current motor and an inverter circuit which drives the alternating current motor, smaller.
In order to achieve the above objects, this invention provides a power module for an inverter which converts a direct current from a direct current power supply source to two types of three-phase alternating current.
The power module comprises a substrate, a first inverter circuit formed on the substrate, and a second inverter circuit formed on the substrate.
The first inverter circuit comprises a first group of switching elements, a first output busbar, a second output busbar and a third output busbar, wherein the first output busbar, second output busbar and third output busbar output a first three-phase alternating current generated by the first group of switching elements.
The second inverter circuit comprises a second group of switching elements, a fourth output busbar disposed in close proximity to the first output busbar, a fifth output busbar disposed in close proximity to the second output busbar and a sixth output busbar disposed in close proximity to the third output busbar, wherein the fourth output busbar, the fifth output busbar and sixth output busbar output a second three-phase alternating current generated by the second group of switching elements.
The first group of switching elements and second group of switching elements, are disposed so that the current flowing in the fourth output busbar and the current flowing in the first output busbar are in opposite directions, and the current flowing in the fifth output busbar and the current flowing in the second output busbar are in opposite directions, and the current flowing in the sixth output busbar and the current flowing in the second output busbar are in opposite directions.